The present invention relates to the deposition of a coating containing silicon and oxygen from vaporized hydrogen silsesquioxane resin. The process comprises introducing the hydrogen silsesquioxane vapor into a deposition chamber containing the substrate to be coated and then inducing reaction of the vapor to form the coating.
Numerous silica vapor deposition methods are known in the art and many are currently used in industry. Typically, such deposition methods involve decomposing a silicon source in the presence of oxygen and the substrate to be coated. For example, chemical vapor deposition (CVD) is used to decompose various silanes (e.g., SiH.sub.4, H.sub.2 SiCl.sub.2, etc.) in the presence of a source of oxygen (e.g., air, oxygen, ozone, NO.sub.2, etc.) for the deposition of protective or dielectric coatings.
Hydrogen silsesquioxane resin is likewise known in the art. For instance, Collins et al, in U.S. Pat. No. 3.615.272 describe such resins and their method of manufacture. Similarly, Haluska et al, in U.S. Pat. No. 4,756.977 teach the use of hydrogen silsesquioxane resin to form ceramic coatings on substrates. These patents, however, only describe the use of the resin in solution.
U.S. Pat. No. 5,063,267 assigned to the same assignee hereof, describes fractionating hydrogen silsesquioxane resin into narrow molecular weight fractions. The application describes the low molecular weight fractions thereof as volatile but does not describe a utility for such materials.
The present inventor has now unexpectedly discovered that gaseous, low molecular weight hydrogen silsesquioxane can be used in conventional vapor deposition techniques to form silicon and oxygen containing coatings.